WASHINGTON (CNN) -- The U.S. Sentencing Commission is considering retroactive changes that could mean shortened sentences for nearly 20,000 federal prisoners convicted of crack cocaine related offenses.
A man known on the street as "Detroit" smokes crack in a drainage pipe in Los Angeles in 2006.
The commission heard Tuesday from a federal judge and advocacy groups who favor making the change retroactive, and from the Justice Department and others who oppose it.
Guidelines that went into effect November 1 already have reduced the disparity between sentences for crack possession convictions and convictions for possessing cocaine in powder form.
Before the changes, a criminal found guilty of having one gram of crack cocaine would receive the same penalty as someone with 100 grams of the powder version.
Advocates for the sentencing change long have argued that disparity especially hurts African-Americans. Depending on various factors, the new guidelines will shorten sentences for crack cocaine by about 25 percent. Watch the both sides make impassioned pleas »
Making the change retroactive would affect an estimated 19,500 prisoners. If the commission approves it soon, about 2,500 prisoners could go free within a year.
So far the commission has received about 33,000 written comments regarding its proposal. There is no set timetable for action.
If the proposal is approved, a judge would examine each eligible prisoner's case. The judge would decide -- based on factors such as the defendant's history and the circumstances of the arrest -- whether to cut the sentence and by how much.
"To those in our society who sometimes believe that our society really doesn't care about them, I think it's important that we send a message that we do," U.S. District Court Judge Reggie Walton said in his testimony. "While we're not going to tolerate aberrant behavior on the part of anybody ... we're going to treat everybody who comes into our court of law equally."
He added, "I do think that fundamental fairness in the end has to control the decision and should dictate whether this becomes retroactive or not."
The Justice Department argued that releasing that many prisoners years earlier than planned could have a dramatic impact on society, especially at a time when rates of violent crime have risen in many parts of the nation.
"I am concerned that if indeed you make the penalties retroactive with regard to the changes in guidelines, that we are going to see an influx of the very people who are most likely to re-offend and are most likely to upset these fragile neighborhoods," said Gretchen Shappert, U.S. attorney for the Western District of North Carolina.
She told the commission that the impact on communities would be "swift" and "sudden" if the changes were made retroactively.
Commissioner Ruben Castillo responded that judges would be expected to use their discretion and to take into account such factors as a defendant's violent history when deciding how to proceed.
Attending the session were at least a dozen families whose relatives could be released early if the commission votes for the proposal.
Karen Garrison, whose twin sons are serving sentences of more than 15 years for crack cocaine possession, told CNN she is hopeful the commission will act.
"I try not to be frustrated because I can't concentrate," she said. "I won't be able to hear the things I need to hear to understand what is going on," she added. "And if I get frustrated it goes into being anxious, maybe even a little bit angry and I can't give in to those things."
Her sons, who have continually vowed they are not guilty, could see their sentences reduced by several years.
"I don't feel anything at this point," Garrison said. "It is like waiting and see. I have been doing that for almost 10 years, just waiting and see." E-mail to a friend
CNN's Carol Cratty also contributed to this report.